In general, a recording apparatus such as a copier or printer is provided with a paper supply cassette holding a stack of sheet paper, a recording unit which performs recording on the sheet paper fed out of the paper supply cassette, and a paper receiver which receives the sheet paper ejected from the recording unit. A paper supply passageway extends between the paper supply cassette and the recording unit, and a paper eject passageway extends between the recording unit and the paper receiver. In short, the sheet paper to be recorded on is introduced from the paper supply cassette to the recording unit through the paper supply passageway, recording is applied to one side of the sheet paper, and this recorded sheet paper is fed to the paper receiver from the recording unit through the paper eject passageway.
Where two-sided recording is applied to sheet paper by such a recording apparatus, after the recording is applied to one side of the sheet paper, it is necessary to reverse that sheet paper and return it to the recording unit. For this reason, in a recording apparatus which can perform two-sided recording, a paper bypass passageway is provided between the paper supply passageway and the paper eject passageway, and a paper switching unit is installed at a branched portion of the paper eject passageway and paper bypass passageway. During one-sided recording, the sheet paper is fed to the paper receiver through the paper eject passageway, but during two-sided recording, the sheet paper is sent to the paper bypass passageway by the paper switching unit. A paper reversal mechanism is installed in the paper bypass passageway, the sheet paper is reversed by the paper reversal mechanism and then introduced again into the recording unit, and thus the recording is applied to the other side of the sheet paper. This sheet paper, that is, the sheet paper subjected to the two-sided recording, is fed from the recording unit to the paper receiver through the eject passageway.
A typical conventional paper reversal mechanism contains a paper reversal and accommodating portion provided midway of the paper bypass passageway, which paper reversal and accommodating portion divides the paper bypass passageway into an upstream part and a downstream part. The paper reversal mechanism further contains a roller assembly installed in the paper reversal and accommodating portion, which roller assembly contains an intermediate roller and two side rollers engaged with this intermediate roller. The intermediate roller is arranged at the branched portion of the upstream part and downstream part of the paper bypass passageway. At this time, one of the two side rollers, that is, a first side roller, is positioned in the upstream part of the paper bypass passageway, and the other side roller, that is, a second side roller, is positioned in the downstream part of the paper bypass passageway. The sheet paper sent through the upstream part of the paper bypass passageway is pulled into the paper reversal and accommodating portion by the first side roller and intermediate roller. When the rear edge thereof leaves the nip between the first side roller and intermediate roller, the rear edge is grasped by the nip between the second side roller and intermediate roller, whereby the sheet paper is sent to the downstream part of the paper bypass passageway by the second side roller and intermediate roller. Thus, a reversal of the sheet paper is obtained, whereby two-sided recording on the sheet paper becomes possible.
As apparent from the above description, in the conventional paper reversal mechanism, at the time of reversal of the sheet paper, the sheet paper must be completely accommodated in the paper reversal and accommodating portion. In other words, the length of the paper reversal and accommodating portion must correspond to the length of the largest size of sheet paper. For this reason, a recording apparatus having a paper reversal mechanism as mentioned above is enlarged in size due to the paper reversal and accommodating portion thereof.